Meeting the resistance challenge

In an era of escalating resistance and increasing critical care patient populations, labs must be able to identify resistant microorganisms, trends in resistance, and emerging resistance patterns among clinically relevant bacteria. ETEST® ARD products simplify the detection and confirmation of resistant phenotypes for the most clinically relevant resistance mechanisms, including ESBLs (Extended-spectrum beta-lactamases), MBLs (Metallo-beta-lactamases) and AmpC beta-lactamases.

The ETEST® ARD strip is calibrated with inhibitory concentration (IC) reading scales in μg/mL on one side and the other carries two predefined antimicrobial exponential gradients, one containing an inhibitor at constant concentration. Set up according to standard ETEST® procedures, the strips generate an inhibitory concentration (IC) ratio used for phenotypic detection of various resistance mechanisms. You detect resistance based on observing differential inhibition. To determine MIC values of individual antimicrobials, use the appropriate ETEST® product containing a single antimicrobial. ETEST® ARD reagent strips extend your resistance detection capacity by:

Detecting resistant phenotypes, including low level expression

Allowing modification of S,I,R categorical results that are inconsistent with inferred resistance mechanisms

Allowing inference of susceptibility results for antimicrobials that are not included in the antibiogram

AmpC ß-Lactamase Detection

For research use only (RUO)

AmpC ß-lactamases (AmpCs) are class C enzymes produced by pathogenic organisms such as Escherichia coli bacteria. They primarily hydrolyze cephalosporins and cephamycins, but also penicillins and aztreonam. Normally AmpC is produced at low levels and doesn’t cause resistance, but higher-level AmpC production can occur as a result of mutation or when the organism is exposed to an inducing agent.

Phenotypic detection of AmpC is easy with the ETEST® AmpC strip. AmpC is induced with cefotetan, then you detect it by comparing the IC on one side, where AmpC is inhibited with cloxacillin, to the other side, where there is no inhibitor.

ETEST® ESBL can be used when ESBL is suspected in strains where MIC values are low or non-determinable by other methods. Testing must be done with at least both ETEST® CT/CTL and TZ/TZL strips. Non-determinable results should be confirmed using ETEST® PM/PML strips.

Glycopeptide Resistance Detection (GRD)

For research use only (RUO)

Staphylococcus aureus is frequently resistant to treatment and in many cases this is due to the presence of intermediate and heterogeneous resistance to glycopeptides (GISA and hGISA, respectively). This resistance cannot be detected with standard MIC determination. The gold standard method, population analysis profile – area under the curve (PAP-AUC), is too laborious to be used in a clinical microbiology laboratory. ETEST® GRD uses a double-sided predefined gradient of vancomycin (VA) and teicoplanin (TP) to simplify detection of GISA or hGISA phenotypes.

Metallo ß-Lactamase Detection

For research use only (RUO) in the United States

Metallo ß-lactamases (MBLs) are class B enzymes whose activity is dependent on divalent cations like zinc or cadmium, so their activity can be inhibited by metal chelators such as ethylenediaminetetraacetic acid (EDTA).

To detect MBL with ETEST® MBL (MBL IP/IPI and MBL MP/MPI) strips, you compare differential inhibition of IC of a carbapenem alone relative to the same carbapenem plus EDTA in the presence of a MBL. ETEST® MBL IP/IPI is used mainly to detect MBLs in Pseudomonas spp. and most Acinetobacter spp.. ETEST® MBL MP/MPI is designed to detect MBLs in Enterobacteriaceae.